【摘要】 通过多种分析方法对华北近三十年来的中强地震震前的地磁异常进行分析 ,发现地震的孕育、发生在时空分布上与地磁场的变化有一定的相关性。震中距 2 0 0km范围内 ,中强地震前很多台站都出现变幅不等的地磁异常变化 ,异常时间多数在一年内。异常形态多为趋势性上升或趋势性下降更多还原

【Abstract】 Analysing North Chinas precursory geomagnetic anomalies of moderately strong earthquakes in the last 30 years using of different geomagnetic methods,it is found that the build-up processes of earthquaks have relation to the variation of geomagnetic field.In the area length of 200 kilometers around the epicentre,there are many anomalous variations occurred in some seismostations before a moderately strong earthquake happens, and the anomalous duration is less than a year.The anomalies ies often shows a increasing or decreasing tendency.更多还原